"The Thin One", along with his husband, "the Fat One", were part of the Anglican Marines of the Church stationed at Demon's Run. They were both discussing the Eleventh Doctor's actions in chasing the Atraxi from Earth after they captured Prisoner Zero and the fact that he called them back to scold them for almost roasting Earth. When Lorna Bucket asked them if they had names, they said that they were the "Thin/Fat Gay Married Anglican Marines" and jokingly asked why they would need names.
His husband was taken to be initiated into the order of the Headless Monks, and when Colonel Manton later revealed what this entailed, he was understandably upset. When the Doctor hid himself in a Monk's robes, he opened fire on one of them in a panic, thinking it was the Doctor. (TV: A Good Man Goes to War)